Hagen is the daughter of Michele and Charlie Hagen. She was a soccer all-state selection for three years at Appleton North High School. At age 15, she was diagnosed with ovarian cancer and underwent a series of surgeries and chemotherapy. She had her last surgery on May 6, 2005.[1]

During Hagen's career at Bayern Munich from January 2012 up until December 2013 she scored 38 goals in the 51 matches in which she played. That total includes 8 matches in which she scored 13 goals in the Frauen DFB Pokal, a championship tournament.[7]

On March 20, 2014, FC Kansas City announced that Hagen would join their team in June 2014 after the end of her season with Bayern Munich.[8] That year, she started seven games in nine appearances recording four goals and one assist.